Fatty amines produced from tallow, coconut oil, palm oil etc. as the starting material are important intermediates in household and industrial fields. Particularly, fatty tertiary amines are converted into quaternary ammonium salts etc. and utilized in a wide variety of applications such as the field of fiber softening finishers, antistatic agents, rinse bases etc.
Conventionally, a method of producing a tertiary amine from an alcohol and a primary or secondary amine as the starting materials is well-known, but the corresponding tertiary amine is hardly obtained highly selectively. For example, JP-B 3-4534 discloses a method of obtaining an objective tertiary amine in high yield by using a catalyst based on copper/nickel/third component. However, even if this catalyst is used, considerable undesired side products are generated when the amount of the catalyst is increased or the reaction temperature is raised for improving manufacturing ability in converting an alcohol into the corresponding tertiary amine in the same reaction system.
Such side products include those generated by the reaction in which a primary or secondary amine as the starting material undergoing disproportionation reaction depending on the action of a catalyst and high-temperature conditions is involved. The reaction of converting a primary or secondary amine into the corresponding tertiary amine is competitive to the disproportionation reaction of a primary or secondary amine, and when a primary or secondary amine is reacted with an alcohol in the same reaction system in the presence of a catalyst at high temperatures in order to obtain the corresponding tertiary amine, generation of the above side products is inevitable in principle.
It has been reported that the reaction of converting an alcohol and a primary or secondary amine into the corresponding tertiary amine proceeds via a plurality of elementary steps. For example, Baiker et al. (Catal. Rev. Sci. Eng., 27(4), 653 (1985)) has confirmed the presence of, as reaction intermediates, an aldehyde generated by dehydrogenation of an alcohol, an imine and/or an enamine generated by adding a primary or secondary amine to the aldehyde and subsequent dehydration thereof. Techniques for carrying out these elementary steps individually and separately are well-known. The step of dehydrogenating an alcohol is disclosed in for example U.S. Pat. No. 2,746,993, the step of adding a primary or secondary amine to an aldehyde is disclosed in for example “Shin Jikken Kagaku Koza 14 Yuki Kagobutsu No Gosei To Hanno III” (New Experimental Chemistry Course 14, Organic Compound Synthesis and Reaction III), p. 1410 and p. 1422, published by Maruzen Co., Ltd. (1978), and the step of hydrogenating an imine and enamine to generate the corresponding secondary or tertiary amine is disclosed in for example “Shin Jikken Kagaku Koza 14 Yuki Kagobutsu No Gosei To Hanno III” (New Experimental Chemistry Course 14, Organic Compound Synthesis and Reaction III), p. 1340, published by Maruzen Co., Ltd. (1978) and The chemistry of enamines, Ch. 17, III, published by John Wiley & Sons Ltd. (1994).
A method wherein a carbonyl group-containing compound or a compound capable of forming a carbonyl group under reducing amination conditions is converted, through reducing amination, into an aminated compound is disclosed in JP-A 3-68541. It is described therein that in a liquid solvent, (a) a carbonyl group-containing compound is contacted with a primary or secondary amine under imine-forming conditions, to form an imino or enamino group-containing compound and then (b) the imino or enamino group-containing compound is contacted with hydrogen under amine-forming conditions to form an amine product, whereby the formation of a hydroxyl group by hydrogenating the carbonyl group can be minimized in the process.